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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.7.10/dist/vue.min.js"></script>
</head>
<body>
    <div id="app">
        请输入张三的成绩：<input type="text" v-model="va" v-on:click="add"  v-on:keyup.enter="submit">
        <h2 v-if="num>=90">张三的成绩优秀</h2>
        <h2 v-else-if="num>=75&&num<90">张三的成绩良好</h2>
        <h2 v-else-if="num>=60&&num<75">张三的成绩及格</h2>
        <h2 v-else="num<60">张三的成绩不及格</h2>
    </div>
    <script>
        new Vue({
            el:"#app",
            data:{
                num:0,
                va:""

            },
            methods:{
                add(){
                this.num++
            },
            submit(){
                this.num=this.va
            }
            }
            
        })
    </script>
</body>
</html>